Undoubted primates first appear almost synchronously in the fossil records of Asia, Europe, and North America. This temporal pattern has complicated efforts to reconstruct the early dispersal history of primates in relation to global climate change and eustatic fluctuations in sea level. Here, I describe fossils from the Tuscahoma Formation on the Gulf Coastal Plain of Mississippi documenting an anatomically primitive species of Teilhardina that is older than other North American and European primates. Consistent with its antiquity, a phylogenetic analysis of dental characters recognizes Teilhardina magnoliana, sp. nov., as the most basal member of this genus currently known from either North America or Europe. Its stratigraphic provenance demonstrates that primates originally colonized North America near the base of the Paleocene–Eocene Thermal Maximum (PETM), but before an important fall in eustatic sea level. Correlation based on carbon isotope stratigraphy and sequence stratigraphy indicates that the earliest North American primates inhabited coastal regions of the continent for thousands of years before they were able to colonize the Rocky Mountain Interior. The transient provincialism displayed by early North American primates corresponds to similar biogeographic patterns noted among fossil plants. Decreased precipitation in the Rocky Mountain Interior during the early part of the PETM may have been an important factor in maintaining biotic provincialism within North America at this time. These results underscore the need to obtain multiple, geographically dispersed records bearing on significant macroevolutionary events such as the PETM.

Beard, K.C. 2008. The oldest North American primate and mammalian biogeography during the Paleocene-Eocene Thermal Maximum. Proceedings of the National Academy of Sciences. 105 (10): 3815. doi:10.1073/pnas.0710180105.

Fig 1.(D) We hypothesize that Teilhardina dispersed through continuous forest from southern Asia to Europe and from nothern Europe to North America during the first 25 Kyr of the PETM.

Abstract

True primates appeared suddenly on all three northern continents during the 100,000-yr-duration Paleocene–Eocene Thermal Maximum at the beginning of the Eocene,55.5 mya. The simultaneous or nearly simultaneous appearance of euprimates on northern continents has been difficult to understand because the source area, immediate ancestors, and dispersal routes were all unknown. Now, omomyid haplorhine Teilhardina is known on all three continents in association with the carbon isotope excursion marking the Paleocene–Eocene Thermal Maximum. Relative position within the carbon isotope excursion indicates that Asian Teilhardina asiatica is oldest, European Teilhardina belgica is younger, and North American Teilhardina brandti and Teilhardina americana are, successively, youngest. Analysis of morphological characteristics of all four species supports an Asian origin and a westward Asia-to-Europe-to-North America dispersal for Teilhardina. High-resolution isotope stratigraphy indicates that this dispersal happened in an interval of 25,000 yr. Rapid geographic dispersal and morphological character evolution in Teilhardina reported here are consistent with rates observed in other contexts.

Tuesday, August 30, 2011

The delimitation of the genus Hoya, with at least 200 species distributed from India and China to Australia, from its closest relatives in the Marsdenieae has long been problematic, precluding an understanding of the evolution and biogeography of the genus. Traditional circumscriptions of genera in the Hoya alliance have relied on features of the ﬂower, but these overlap extensively between clades and may be evolutionarily labile. We obtained chloroplast DNA sequences to infer the phylogenetic relationships among a sample of 35 taxa of Hoya and 11 other genera in the tribe Marsdenieae, namely Absolmsia, Cionura, Dischidia, Dregea, Gongronema, Gunnessia, Madangia, Marsdenia, Micholitzia, Rhyssolobium, and Telosma. Trees were rooted with representatives of Asclepiadeae, Ceropegieae, Fockeeae, Periplocoideae, and Secamonoideae. Hoya and Dischidia form a monophyletic group, but the phylogenetic signal in the chloroplast data analyzed here was insufﬁcient to statistically support the mutual monophyly of the two genera. A monophyletic Hoya, however, must include the monotypic Absolmsia, Madangia, and Micholitzia, a result congruent with their ﬂower morphology. The data also identiﬁed several well supported groups within Hoya. The morphologically unusual Gunnessia belongs ﬁrmly in the Marsdenieae, but it is not close to Hoya and Dischidia.

Monday, August 29, 2011

The new species Hoya persicinicoronaria S. Y. He & P. T. Li (Apocynaceae, Asclepiadoideae) is described and illustrated from Hainan, China. The morphology of the related species H. pottsii Traill and H. liangii Tsiang are compared to the new species, which differs in its indumentum, leaf arrangement, leaflet pattern, leaf shape, apex, and size, calyx shape, and corolla color.

A new species, Hoya bawanglingensis S. Y. He & P. T. Li (Apocynaceae, Asclepiadoideae), is described and illustrated from Hainan, China. The morphological characters of H. bawanglingensis and the related species H. pottsii Traill are compared. Hoya bawanglingensis differs in the pubescence of its young stems, both leaf surfaces, petioles, peduncles, pedicels, outer calyx lobes, and follicles. The corolla lobes are white with purple spots, and the corona is white with a purplish center.

Hoya baishaensis S.Y. He & P.T. Li sp. nova (Apocynaceae) from Hainan, China is described and illustrated. The morphological characteristics of H. baishaensis and the fairly similar H. griffithii and H. radicalis are compared. Hoya baishaensis differs in its leaf shape, pedicel, calyx and corolla color.

A new species in Apocynaceae, Heterostemma xuansonense T. B. Tran & Joo-Hwan Kim, is described from Vietnam; illustrations and a comparison with related species are also provided. Heterostemma xuansonense distinctly differs from H. grandiflorum Costantin by the flower color, the absence of a peduncle, and the size of the corona.

Heterostemma pingtaoi S. Y. He & J. Y. Lin (Apocynaceae, Asclepiadoideae) is described from Hainan Province, China. The new species is morphologically similar to H. oblongifolium Costantin in its leaf blade with an acute apex and rounded base. In comparison, H. pingtaoi differs from H. oblongifolium in its pubescent petioles (vs. glabrous), the leaves only to 7.3 cm long (vs. 7.5–14 cm), the five calyx glands (vs. 10), and the corolla externally

pubescent and yellow-green with mauve pubescence (vs. green and glabrous).

A new species of Phyllagathis (Melastomataceae), P. nanakorniana, from Thailand is described and illustrated from recently collected material. The morphological characteristics are discussed in view of a wider generic concept that allows the inclusion of P. nanakorniana in Phyllagathis. A key to the Thai species is provided.

While revising the Melastomataceae for the Flora of Thailand, we discovered two new species of Sonerila, as well as the need for transferring two species of Tylanthera endemic to Thailand into Phyllagathis. Sonerila urceolata and S. loeiensis are endemic to the southeast and the northeast of Thailand, respectively. The first is allied to the widespread S. erecta Jack, from which it differs mainly in the strongly urceolate capsule and the sessile fruit placenta; the second is distinguished from other acaulescent species of Sonerila by its extremely longetiolate large leaves and long-pedunculate inflorescence. The new combinations, Phyllagathis tuberosa (Hansen) Cellinese & Rennerand P. siamensis Cellinese & Rennernom. nov., are made because both taxa lie inside the morphologic and phylogenetic bounds of Phyllagathis

The two new species SonerilaanaimudicaLundin & B. Nordenstam and S. coriacea Lundin & B. Nordenstam, from Kerala and Tamil Nadu, respectively, are recognized in connection with a taxonomic revision of the South Indian species of Sonerila Roxburgh (Melastomataceae). Descriptions, discussions, and illustrations are provided. Both species are endemic to the Western Ghats in South India. Sonerila anaimudica is a small succulent herb, and the usually single terminal flower has very obtuse or even retuse obovate petals with glandular margins. Sonerila coriacea is a somewhat woody succulent herb with a coriaceous layer on the stems, coriaceous leaves, and showy racemose flowers. Both species have restricted distribution and small populations and are regarded as Vulnerable (VU) and Endangered (EN), respectively, based on IUCN Red List criteria.

Sonerila vatphouensis(Melastomataceae), a new species from Laos. A new species of Sonerila, related to S. tuberosa based on its tubercules and foliar dimorphism, is described and illustrated. The new species has foliar glands, previously noted in the genus only from S. neodriessenioides. However, the foliar glands of Sonerila vatphouensis are oblong, as are those of the monotypic genus Stussenia, while those of Sonerila neodriessenioides are peltate.